import java.util.Scanner;

public class Demo2 {
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		int num;
		int result;
		String str;
		System.out.println("输入一个数：");
		while (!input.hasNextInt()) {
			str = input.next();
			System.err.println("输出的" + str + "不是整数，重新输入：");
		}
		num = input.nextInt();
		result = (int) ((num * 10 + 5) / 2 + 3.14159);
		System.out.println(result);
	}
}
